Method of and apparatus for reducing metals, etc.



A. BRIDGE.

METHOD OF AND APPARATUS FOR REDUCING METALS, ETC,

APPLICATION FILED MAY29,1919.

Patented May 9, 1922.

anventoz EUR BRIDGE, OF WASHINGTON, DISTRICT OI CO LUIA.

Emerson or AND APP teasers.

Specification of Letters Patent.

mus son nnnncmem'e'reas, are.

Patented -May 9, 1 .922,

Application filed May igfi, 1919. Serial No. 300,587. 7

To all whom it mag concern:

Be it known that I, ARTHUR Bgnipcn, a citizen of the United States, residing at Washington, in thep'District of Columbia,

have invented certain new and useful'Improvements in Methods of and Apparatus for Reducing Metals, Etc, of which the following is a specification, reference being had to the accompanying drawings.

, This invention relates to processes for reducing the oxides of metals, such as columbium, molybdenum, tantalum, titanium, tungsten, vanadium and zirconium,' and metalloids by means of a thermal reaction with such metals as aluminum, magnesium, and calcium which unite with oxygen to form oxides with great heat of formatlon.

An object of m inventionis to provide a rocess which wil secure pure metals, metaloids and alloys having definite, predetermined roportions of two or more metals or metalloids, and to perform allotropic modifications on elements subject 7 to allotropic changes. under high heat and pressure.

And a further object is toso control the production of the reaction that there shall be no possibility of explosion-iwhich will scatter the materials used.

' I attain these objects, broadly speaking,

excluding the oxygen and nitrogen in the air;

from enteringinto the reaction by carrying out the reduction process in an entirely closed chamber, and further by using as the means for setting up the thermal reaction an ignition element having the same chemical element as one of the chemicalelements entering into the reaction, or by using an ex tremely small quantity of' solid material of diil'erent chemical'elements than-the chemical elements entering into the reaction,

The mechanism whereby the process is carried out is illustrated in the accompanying'drawings, wherein j I a Figure 1 is a longitudinal section of an apparatus constructed in accordance with my invention; v

Figure 2 is a fragmentary View of the igniting wire and its insulation;

Figure 3 is a vertical" section of another form of apparatus;

Figure 4 is an enlarged fragmentary section of the apparatus:

Figure 1t; and

I face of the Figure 5 is a section on the line 5-'5 of trated in Figure 1, to carry out my process,

I provide a steel cylinder 10, made preferably of seamless, hydraulic steel tubing. Into the ends of this steel cylinder are screwed two heavy steel plugs 11 and 12, thus forming a chamber 13. The plug 11 has a central bore through which is disposed an insulated wire 14. This insulated wire 14 extends through to the interior of the plug 11, the extremity of the insulated wire protruding but a very short distance beyond the inner face of the plug 11. To this end of the insulated wire I attach a wire 15 which is looped and attached'by a binding screw 16 or other suitable connection to the inner plug 11. The exterior of'the plug is provided with a binding screw 17. Electrical connections may be made to the insulated wire 14 and to the binding screw 17. The loop of wire 15 is of such length that it will extend some distance toward the center of the cylinder when the plug is screwed into position. The wire loop 15 should have, of course, a higher resistance than the wire 14, and this wire' may be formed of a metal corresponding to the metal used in reduction, as for instance, aluminum, magnesium, or calcium, and under these circumstances the wlre loop 1s to be insulated w1th its own oxlde or a coatmg of the oxide to be reduced, or by its own peroxide or a peroxide of the metal to be reduced. In place of such a wire loop as above described, a loop of fine iron wire may be used which is insulated up to a short distance of where it is attached to the insulated wire 14 and binding screw 16 by a layer of tissue paper soaked in a concentrated solution of potassium chlorate, with magnesium powder sprinkled on this insulated layer of tissue paper while it is wet, (see Figure 2) and then dried. The loop of wire of the character before described is designed to serve as an ignition means for startin the thermal reactlon, and where aniron wire is used, it may be so small that the chemical elements, iron, carbon, hydrogen, chlorine and potassium, will be found only as minute traces in the final product of the thermal rev with a rather stable oxide, may also be heated by a-current below its fusing point to heat the surrounding material for some time "before current of greater amperage is aping lining 18 is formed within the cylinder.

This lining may consist of such materials as aluminum oxide, ma esium oxide, or calciu'm oxide. Each 0 these oxides is a very poor conductor of heat and very refractory. The oxides are used in the form .of a calcined powder which isso filled into the cylinder as to provide a central space. The

oxide used may correspond to the oxide formed by the thermal reaction, which is of advantage when it is desired to recover as a byroduct an unmixed oxide. This centra l space is to be filled with a reduction mixture 19, that is a mixture of the oxide of the metals or metalloids to be reduced,

' with one of the reducing metals as aluminumg magnesium, or calcium in a chemically uncombined form. This reduction mixture is in the form of a powder but not necessarily a fine owder except near wire 15, and the constituents of the reduction mixture are mixed in practically the same ratio of proportions by weight as the'ratio of their chemical equivalent weights found in a chemical equation representing the reaction. In filling the cylinder, the heat insulating material is packed within the cylinder so as to leave a cavity in the middle into which loop 15 projects. This cavity is filled with the reduction mixture and then a layer of the heat insulating material is packed over it so that the heat insulating material now entirely surrounds the reduction mixture. The plug 12 is next screwed The ignition wire is now connected in an electric circuit and the wire is fused by ourrent of sufiicient amperage. whereupon the thermal reaction is started'and takes place, this being evidenced by the heating of the cylinder. The cylinder and contents are allowed to cool before the contents are taken out and separated.

Where the process 'is to be carried out on a relatively extensive scale, the apparatus shown in Figure 3 would be preferably used.

In this case, 20 designates a metallic form or holder having therein connected chambers 21 and 22, the chamber 21 being smaller in diameter than the chamber 22, and there being an opening 23 communicating with the chamber 22 adjacent its junction with the chamber 21, Disposed within the chamber 22 is a piston 24 having a length longer than the size of the opening 23, the chamber 22, however, being of sufiicient length so that the (p1ston 24 can move back into the outer en of the chamber.- 22 to disclose the'opening 23. Disposed within the chamber,21 is a piston 25, and the chambers 21 and 22 are connected b ducts 26 to means chambersto: thereby force these istons 24 and 25 towards each other. The t ermal reaction is carried out within a metallic case 29 having a loose cover 30, which is'ada ted to fit within the" chamber 21. and which contaips an outer layer of heat insulating material 18; surrounding a'v central mass 19 of the reducing mixture. The i ition means 1n this instance consists of-a 00p of -wire 15 connected to double leads 14' which extend out through the top or cover 30 and extended laterally in a groove therein, which groove is filled with cement after the crucible lid is set on the crucible 29, the wires being carried out through the opening 23. Ofcourse, I do not wish to be limited to :this, as other means of ignition might be provided.

With an apparatus of this character, the

thermal reaction is precisely the same as in" whereby fluid under high pressure, as for 'insta-nce, ;water may be forced into these into the chamber 21, and when the piston 24 has fully seated and fully closes the opening 23, then the piston 25 is urged upward until it seats against the case 29. Thus, the case is entirely surrounded by heavy metallic walls which will resist the pressure generated within the case and prevent the case from being ruptured. After a certain lapse of time, during which the reaction is completed, the pressure of the confined gases is relaxed by relieving the hydraulic pressure behind the piston 24 a little. The pressure within the container or crucible 18 will then raise the lid 30 a trifle, permitting the gases "to escape through the opening 23. After this, the hydraulic pressure is applied behind the piston 25 and relieved from behind the piston 24 to cause the upward movementof the pistons 25 and 24 to carry the case 29 and its contents into position in front of the opening 23 and permit the removal of the case by tongs.

While I have hereto ore descrlbed the Lemme lining of thecrucible by simply packing a powdered heat insulating materlal around.

wall of the crucible may be formed by fitjting the metal shell of the crucible, illustrated in Figure 1, or the metal shell of the container 29, with a temporary water jacket connected by flexible hose to a source of water. The magnesium oxide may be apliedfby means of an electric are brought lnto contact with unfused magnesium oxide placed within the cylinder. This melts the magnesium oxide near the arc and causes it to adhere to the water cooled metal crucible. Small quantities of magnesium oxide are added as needed and the are shifted, and thus a complete interior lining ma built up' within the crucible, this lining being applied by .the means above described to the head or end of the crucible.

It will be seen that with the construction described, I reduce metals, metalloids and alloys without the oxygen and nitrogen of the air entering into the chemical reaction at all. This is particularly essential in the case of refractory acid forming metals which will not readily fuse into a regulus, and in some cases will not fuse into a regulus at all, and as they combine with oxygen and nitrogen while at a high temperature, they cannot be reduced in the air by a thermal reaction without causing a secondary reaction with the oxygen and nitrogen of the air. directly after being reduced. This secondary reaction is alwaysmore or less'complete accordingto the physical condition and chemical nature of the metal reduced.

It will be noted that there is no secondary reaction where my process and apparatus is used. Furthermore, my process is advantageous in that as the space in which the reaction takes place is entirely enclosed, there can be no volatilization of the metal acting as the reducing agent or'the metal oxide being reduced. Furthermore, by having this process take place in an entirely closed chamber, there is no scattering of the material used in the reduction and no heat is lost by the unrestricted expansion of the volatile material, and there is no possibility of explosions occurring which would scatter or displace the material being treated. 'Heretofore, the reduction of such metals as 00 lumbium, molybdenum, etc., have been socured by means of carbon reduction in an electric arc furnace. This produces brittle metals with a carbon content in the cases of these metals as columbium, tantalum, vanadium, zirconium, molybdenum and others. Carbon free metal has been produced by pulverizing the reduced metal, mixing it with suflicient metallic oxide to react with the carhon, and the reduction efiected by insertion in a crucible in an arc furnace, but my method has an advantage over the one just described, in that thereis only one operation instead of two, and further the secondary reactions with air are entirely eliminated.

The method heretofore described and an apparatus, similar to that illus'tratedin Fig. ure 1, is also adapted for the purpose of'producing an allotropic form of carbon, in other words roducing'a diamond. In Figure 6, I show the same form of cylinder as is illustrated in Figure 1. I use a reduction mixture 32' which is composed of magnesium carbonate and metallic magnesium (MgcO l- Mgf. An insulating lining 33 of used or powderedmagnesium oxide is also used between the mass of the reduction mixture 32 and the walls of the crucible.-

Disposed in the lower portion of the mass of reduction mixture is a lump 34' of pure carbon, as for instance, in the form of graphite, and disposed within the mass of the reduction mixture is a container 35 of magnesium which is filled with some inert gas under compression, as for instance, agas of the helium series, such as argon. v

It will be seen that the process just above described is but a carrying forward of the process previously described, in that the same process of thermal reaction is usedbut the heat and pressure produced; by this reaction is used to change the form of an allotropic element. The purpose of the container 35 with its compressed helium gas is to cause the pressure to be maintained within the chamber until the critical temperature necessary for the production of a diamond has passed, the expansion of the gas after the reduction has been secured maintaining this pressure. Without this container and gas, the necessary pressure would not be maintained. It W111 be seen that this process is similar to the process of metal reduction heretofore described, in that the magnesium carbonate corresponds to the metallic oxide. It difiers from the previous process, however, merely in the fact in the use of the small gas container and the disposal within the chamber of a lump of graphite to be acted on by the heat and pressure.

In the reaction of the magnesium-magnesium carbonate mixture, the magnesium carbonate is not decomposed into the components Mg-l- C-l-SO having 266.6 calories but the magnesium remains combined with its equivalent oxygen, the components being MgO-l-C-I-20. This takes 143.3 cal., the heat of formation of Mg-I-O from 266.6 cal., which gives 123.3 cal., then the heat re re sented by the reaction of 2Mg on Mg 0, would be 143.3X2123.3, which gives 163.3 cal., an exothermic reaction in which great heat is developed.

Graphite, in common with other materials, increases greatly in compressibility by the application of heat and "under the reaction used b my method great heat is developed. As be ore stated, the recation secures 163.3 calories of heat and this amount of heat applied to- 133 grams of material having approximately an average specific heat of .3 will give a temperature of nearly 4000 C. above the temperature before reaction. With asmall piece of graphite heated above 3000 C. a very great ressure is not believed to be necessary in or er to convert it into a diamond and if the inert gas was heated to, say 2730above its original temperature and would expand to twice its volume after release, it would exert five times the pressure it was originally under in the container and this original pressure may easily be 200 atmospheres. It is believed, therefore, that ample pressure would be secured to secure the allotropic modification under the reaction described.

Another method of carrying out an allotropic modification onelements subject to allotropic changes under high heat and ressure is to use such a construction as that illustrated in Fi ures 1 or 6, but in place of usin a container 35 holding insert gas, I woul simply use with the reduction mixture, composed of the oxide of the metals or metalloids to be reduced, with one of the reducing metals, as aluminum, magnesium or calcium in a chemically uncombined' form, an excess of magnesium, in case magnesium is used, which forms a metallic vapor or liquid when the reaction takes place, thus securing the desired pressure within the cylinder, which pressure is maintained within the cylinder or chamber until the critical temperature necessary for the production of a diamond has passed by the vaporization of the excess magnesium after the reduction has been secured. The wire 15 in this case should be relatively long and preferably of magnesium coated with magnesium oxide. The contents of the crucible should be preheated by wire 15 before the reaction is started. This process differs from that previously described with reference to Figure 6, merely in the fact that in this last case I use an excess of magnesium and preheat the contents of the chamber.

In Figures 1 and 6 I have illustrated the plugs 11 and 12 as being formed with air vents which are opened when the plugs are inserted to permit the outward passage of air and which are then closed by plugs 36.

I claim 1. A method of reduction which consists in disposing within a closed, air-tight, pressure resisting chamber a mass of mixed materials of such a nature that they will undergo thermal reaction upon initial ignition, insulating said mass from the walls of the chamber, and causing an initial ignition of the mass to thereby effect reduction.

2. Av method of reduction which consists in disposing within a losed, air-tight, pressure resisting chamber a mass of mixed materials of such a nature that they will undergo a thermal reaction upon an initial ignition, insulating said mass from the walls of the chamber, causing an initial ignition of the mass, releasing the pressure of gas within the chamber after the reduc tion is completed, and removing the reduced material from the chamber.

3. A method of. reducing the oxides of metals and metalloids which consists in disposing within a closed, air-tight and pressure resisting chamber a mixture of oxides of the material to be reduced with a metal which unites with oxygen to form oxides with high heat of formation, insulatin the mixture thus formed from the wall 0 the chamber, and initially igniting the material to start the reaction.

4. A method of reducing the oxides of metals, metalloids and alloys, which consists in disposing within a closed, air-tight and pressure resisting chamber a mixture of the oxide of the metal to be reduced together with a metal which will unite with oxygen to form an oxidewith high heat of formation, and insulating the reducing mixture so formed from the walls of the chamber b a layer of an oxide of a metal correspon ing to. the oxide to be formed by the thermal reaction, and initially starting 7 the reaction by igniting the mixture.

5. A method of reducing the oxides: of

refractory acid forming metals such as.

columbium, molybdenum, tantalum, titanium, tungsten vanadium, etc., by means of l a thermal reaction with such metals as alu-' minum, magnesium, and calcium, which consists in lining a closed, air-tight and pressure resisting chamber with a layer of heat insulating material composed of theparticular oxide to the formed by the thermal reaction, said material being in the form of a calcined powder, then filling the space enclosed by the heat insulating material with a mixture of the oxide of one of the refractory acid forming metals with one of the reducing metals in a chemically uncombined form, the mixture being in the lining a closed, air-tight and pressure resisting chamber with a heat insulating lining composed of the particular oxide corresponding to the oxide to be formed by the thermal reaction, disposing within the space modification of amineral body by subjecting it simultaneously to high pressure and a temperature sufliciently h gh to secure such modification, which consists in dlsposing within a closed, air-tight and pressure resisting chamber lined with insulating material, a reduction mixture comprlsing an oxide of a metal or metalloid with a reducing metal in a chemically uncombined state, disposing within said mass of reduction mixture a lump of the mineral to be mod1- lied, and disposing within the mass of reduction mixture a fusible body which, when subjected to a high temperature, wlll liberate a gaseous elastic vapor, and heating and igniting the reductlon mixture to start thermal reaction within said chamber to thereby produce a high temperature and simultaneously fuse the sald body to secure and maintain an extremelv hlgh pressure within the chamber while the modificatmn scribed comprising a chamber having relatively heavy walls, and having a filling opening and means for closing said opening, onewall of the chamber having extending through it an insulated -wire, and a loop of electrically fusible metal connected to said Wire and extending into the interior of the chamber.

9. A mechanism 'of the character described comprising a hollow body having relatively thick walls and formed to provide two connected chambers having different diameters, one chamber opening directly into the other, pistons, one in each chamber,'means for applying pressure to said pistons to force them towards each other, the wall of the larger chamber having an opening normally closed by the piston of the larger chamber when it is forced fully in one direction but disclosed by said piston when it is forced fully in the other direction into the space between saidpistons, and including an electrically fusible, metallic loop.

In testimony whereof I hereunto aflix my signature in the presence of two witnesses. ARTHUR BRIDGE.-

1 Witnesses: 1

FREDERIC R. WRIGHT,

. Ronnn'r A. BOSWELL. 

